From 181b53e270ff7c0558edec75b8b255d487e796c3 Mon Sep 17 00:00:00 2001
From: 杨宇千 <crupest@outlook.com>
Date: Fri, 25 Oct 2019 23:03:36 +0800
Subject: Add user detail service.

---
 Timeline/Services/UserDetailService.cs | 102 +++++++++++++++++++++++++++++++++
 1 file changed, 102 insertions(+)
 create mode 100644 Timeline/Services/UserDetailService.cs

(limited to 'Timeline/Services/UserDetailService.cs')

diff --git a/Timeline/Services/UserDetailService.cs b/Timeline/Services/UserDetailService.cs
new file mode 100644
index 00000000..0b24e4e2
--- /dev/null
+++ b/Timeline/Services/UserDetailService.cs
@@ -0,0 +1,102 @@
+using Microsoft.Extensions.Logging;
+using System;
+using System.Linq;
+using System.Threading.Tasks;
+using Timeline.Entities;
+using static Timeline.Resources.Services.UserDetailService;
+
+namespace Timeline.Services
+{
+    public interface IUserDetailService
+    {
+        /// <summary>
+        /// Get the nickname of the user with given username.
+        /// If the user does not set a nickname, the username is returned as the nickname.
+        /// </summary>
+        /// <param name="username">The username of the user to get nickname of.</param>
+        /// <returns>The nickname of the user.</returns>
+        /// <exception cref="ArgumentNullException">Thrown when <paramref name="username"/> is null.</exception>
+        /// <exception cref="UsernameBadFormatException">Thrown when <paramref name="username"/> is of bad format.</exception>
+        /// <exception cref="UserNotExistException">Thrown when the user does not exist.</exception>
+        Task<string> GetNickname(string username);
+
+        /// <summary>
+        /// Set the nickname of the user with given username.
+        /// </summary>
+        /// <param name="username">The username of the user to set nickname of.</param>
+        /// <param name="nickname">The nickname. Pass null to unset.</param>
+        /// <exception cref="ArgumentNullException">Thrown when <paramref name="username"/> is null.</exception>
+        /// <exception cref="ArgumentException">Thrown when <paramref name="nickname"/> is not null but its length is bigger than 10.</exception>
+        /// <exception cref="UsernameBadFormatException">Thrown when <paramref name="username"/> is of bad format.</exception>
+        /// <exception cref="UserNotExistException">Thrown when the user does not exist.</exception>
+        Task SetNickname(string username, string? nickname);
+    }
+
+    public class UserDetailService : IUserDetailService
+    {
+        private readonly DatabaseContext _database;
+
+        private readonly ILogger<UserDetailService> _logger;
+
+        public UserDetailService(DatabaseContext database, ILogger<UserDetailService> logger)
+        {
+            _database = database;
+            _logger = logger;
+        }
+
+        public async Task<string> GetNickname(string username)
+        {
+            var userId = await DatabaseExtensions.CheckAndGetUser(_database.Users, username);
+            var nickname = _database.UserDetails.Where(d => d.UserId == userId).Select(d => new { d.Nickname }).SingleOrDefault()?.Nickname;
+            return nickname ?? username;
+        }
+
+        public async Task SetNickname(string username, string? nickname)
+        {
+            if (nickname != null && nickname.Length > 10)
+            {
+                throw new ArgumentException(ExceptionNicknameTooLong, nameof(nickname));
+            }
+            var userId = await DatabaseExtensions.CheckAndGetUser(_database.Users, username);
+            var userDetail = _database.UserDetails.Where(d => d.UserId == userId).SingleOrDefault();
+            if (nickname == null)
+            {
+                if (userDetail == null || userDetail.Nickname == null)
+                {
+                    return;
+                }
+                else
+                {
+                    userDetail.Nickname = null;
+                    await _database.SaveChangesAsync();
+                    _logger.LogInformation(LogEntityNicknameSetToNull, userId);
+                }
+            }
+            else
+            {
+                var create = userDetail == null;
+                if (create)
+                {
+                    userDetail = new UserDetail
+                    {
+                        UserId = userId
+                    };
+                }
+                userDetail!.Nickname = nickname;
+                if (create)
+                {
+                    _database.UserDetails.Add(userDetail);
+                }
+                await _database.SaveChangesAsync();
+                if (create)
+                {
+                    _logger.LogInformation(LogEntityNicknameCreate, userId, nickname);
+                }
+                else
+                {
+                    _logger.LogInformation(LogEntityNicknameSetNotNull, userId, nickname);
+                }
+            }
+        }
+    }
+}
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